title: Studies on the alkaloids of the bark of Magnolia officinalis: isolation and on-line analysis by HPLC-ESI-MS(n).
abstract: The bark of Magnolia officinalis is a well-known Traditional Chinese Medicine. In the present study, two new alkaloids, named (S)-4-keto-magnoflorine (6) and (R)-3,4-dehydromagnocurarine (11), together with seven known alkaloids: (S)-magnoflorine (5), trans/cis N-feruloylputrescine (7/8), (R)-magnocurarine (10), (S)-tembetarine (12), (R)-oblongine (14), and (R)-asimilobine (17) were isolated and their structures elucidated by spectroscopic methods, including 1D, 2D NMR, and HRESI-MS. The absolute configurations of the isoquinoline alkaloids 5, 6, 10-12, 14, and 17 were determined by CD. In vitro inhibitory activities against aldose reductase, lipase, α-glucosidase, DPP-IV and three cancer cell lines (A549, Bel-7402, and HCT-8) were evaluated for all isolated compounds. However, all compounds showed weak activities in all tests at the same concentration as the positive control drugs. An HPLC-ESI-MS(n) method has been established for screening of alkaloids in the bark of M. officinalis. A total of 23 alkaloids were identified or tentatively characterized; including 13 aporphines, eight benzylisoquinolines and two amides. Plausible fragmentation pathways of the representative compounds 6, 7/8, 11, and 17 were proposed in the present study.
authors.affiliation: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China.
authors.forename: Renyi
authors.initials: R
authors.lastname: Yan
authors.forename: Weihao
authors.initials: W
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Guo
authors.forename: Hongliang
authors.initials: H
authors.lastname: Liu
authors.forename: Jianyong
authors.initials: J
authors.lastname: Zhang
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D004353:Drug Evaluation, Preclinical; D006801:Humans; D031566:Magnolia / Q000737:chemistry*; D008516:Medicine, Chinese Traditional; D024301:Plant Bark / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000470:Alkaloids; D000972:Antineoplastic Agents, Phytogenic